base: Remove now-unused MessagePumpObserver.

base/message_loop/message_loop.cc

Index: base/message_loop/message_loop.cc
diff --git a/base/message_loop/message_loop.cc b/base/message_loop/message_loop.cc
index a7217eba2f7284af95a85bb768c69f44820fc9b5..c0d9b0e50ed5ab3be12355994246dd943ec2929a 100644
--- a/base/message_loop/message_loop.cc
+++ b/base/message_loop/message_loop.cc
@@ -662,16 +662,6 @@ void MessageLoopForUI::Attach() {
 }
 #endif
 
-#if defined(OS_WIN)
-void MessageLoopForUI::AddObserver(Observer* observer) {
-  static_cast<MessagePumpWin*>(pump_.get())->AddObserver(observer);
-}
-
-void MessageLoopForUI::RemoveObserver(Observer* observer) {
-  static_cast<MessagePumpWin*>(pump_.get())->RemoveObserver(observer);
-}
-#endif  // defined(OS_WIN)
-
 #if defined(USE_OZONE) || (defined(USE_X11) && !defined(USE_GLIB))
 bool MessageLoopForUI::WatchFileDescriptor(
     int fd,